At scrum time

When a scrum is formed the 8 forwards from each team
bind together to form their own pack.
The two packs then oppose each other by binding
together, head to head with a tunnel between the two packs.

The scrum-half of the non-offending team
puts the ball in to the scrum
but only when the hooker is ready and waiting.

If the forwards do a good job the ball moves through the scrum
to the feet of the number-eight. You or the number 8 pick it up

Prior to that
decisions about what to do with the ball
have been made and
confirmed, perhaps by coded signals.

These decisions are now carried out.

They could include

a lightening fast attacking run by the scrum-half

a move involving the number-eight and the scrum-half

a tactical kick by the scrum-half

whipping the ball out to the backs

As scrum-half you will be in the thick of it and you must
have superior running, handling, kicking and thinking skills.

Play may not go according to plan. The ball may not come out of the scrum cleanly
or the scrum may wheel. You must be razor sharp, able to size things up and
use your skills to make the best of the situation.

When the other team gets the ball you harass their scrum-half and provide
covering defense.

The continuity of play breaks down often.

Players are tackled, fall, drop the ball or fail to catch it.
The result is a breakdown where any number of players
(usually the forwards) get
involved trying to win possession of the ball.

As scrum-half you will make sure you are right there to take the ball
from the ball winners and move it on to where it can be used to
best advantage.